What to do if I lost my recovery key?

See -> Two-step verification for Apple ID

Two-step verification for Apple ID – Apple Support (UK)

👉 scroll to & read -> What if I lose my Recovery Key?

You can sign in to your Apple ID account page and create a new Recovery Key using your Apple ID password and one of your trusted devices.

1 Go to appleid.apple.com/uk.

2 Sign in with your password and trusted device.

3 In the Sign-In and Security section, click Recovery Key > Change Recovery Key.

Keep your new Recovery Key in a safe place. Your old Recovery Key won't work any more and you can't use it to reset your password or access your account. If you can't see Recovery Key in the Sign-In and Security section, then you are not using two-step verification. 

FYI: write down your recovery key and keep it in a safe place.

IF you still have a trusted device signed-in to that “old” account, follow Raicya’s direction to change your password to something memorable.

But IF you have no trusted devices still signed in to that account … AND don’t know your password … AND created a Recovery Key (but no longer have access to it) …

… you’ll not be able to access that account again.

(By generating a recovery key and effectively “super-securing” the AppleID, you’ve also “turned off” Apple’s ability to perform an Account Recovery on your request.)

See:

How to generate a recovery key - Apple Support

Re: “… I forgot my [AppleID] password … “

You’re logged-in here w/ an AppleID and Password. (perhaps w/ your credentials automatically entered by your device)

Are we discussing the same account?

If so, you can most likely reset your AppleID password to something more memorable as described here:

If you forgot your Apple ID password - Apple Support

I forgot my password that’s the problem

See -> If you can't connect or sign in to iCloud

If you can't connect or sign in to iCloud - Apple Support

See -> Change your Apple ID password -> Change your Apple ID password - Apple Support

Then see this Apple article: What to do after you change your Apple ID or password

What to do after you change your Apple ID or password - Apple Support

Best of luck going forward.